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Reimplement scm_is_mutable_pair using gc_heap_contains

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* libguile/pairs.c (scm_to_ref): Copy this stub around again; we should
fix this...
(scm_is_mutable_pair): Use gc_heap_contains.
This commit is contained in:
Andy Wingo 2025-05-04 15:15:41 +02:00
parent fd921be76c
commit fcf8fa3d10
2 changed files with 22 additions and 25 deletions
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21
libguile/pairs.c
View file

@ -1,4 +1,4 @@
/* Copyright 1995-1996,2000-2001,2004-2006,2008-2013,2017-2019
/* Copyright 1995-1996,2000-2001,2004-2006,2008-2013,2017-2019,2025
Free Software Foundation, Inc.
This file is part of Guile.
@ -26,6 +26,7 @@
#include <verify.h>
#include "boolean.h"
#include "gc-internal.h"
#include "gsubr.h"
#include "pairs.h"
@ -74,6 +75,24 @@ scm_cons2 (SCM w, SCM x, SCM y)
return scm_cons (w, scm_cons (x, y));
}
static inline struct gc_ref scm_to_ref (SCM scm)
{
return gc_ref (SCM_UNPACK (scm));
}
int
scm_is_mutable_pair (SCM x)
{
/* Guile embeds literal pairs into compiled object files. It's not
valid Scheme to mutate literal values. Two practical reasons to
enforce this restriction are to allow literals to share share
structure (pairs) with other literals in the compilation unit, and
to allow literals containing immediates to be allocated in the
read-only, shareable section of the file. Attempting to mutate a
pair in the read-only section would cause a segmentation fault, so
to avoid that, we really do need to enforce the restriction. */
return scm_is_pair (x) && gc_heap_contains (the_gc_heap, scm_to_ref (x));
}
SCM_DEFINE (scm_pair_p, "pair?", 1, 0, 0,
(SCM x),

26
libguile/pairs.h
View file

@ -1,7 +1,7 @@
#ifndef SCM_PAIRS_H
#define SCM_PAIRS_H
/* Copyright 1995-1996,2000-2001,2004,2006,2008-2010,2012,2018
/* Copyright 1995-1996,2000-2001,2004,2006,2008-2010,2012,2018,2025
Free Software Foundation, Inc.
This file is part of Guile.
@ -199,29 +199,7 @@ scm_cdr (SCM x)
}
#endif
#ifdef BUILDING_LIBGUILE
#ifndef HAVE_GC_IS_HEAP_PTR
static int
GC_is_heap_ptr (void *ptr)
{
return GC_base (ptr) != NULL;
}
#endif
static inline int
scm_is_mutable_pair (SCM x)
{
/* Guile embeds literal pairs into compiled object files. It's not
valid Scheme to mutate literal values. Two practical reasons to
enforce this restriction are to allow literals to share share
structure (pairs) with other literals in the compilation unit, and
to allow literals containing immediates to be allocated in the
read-only, shareable section of the file. Attempting to mutate a
pair in the read-only section would cause a segmentation fault, so
to avoid that, we really do need to enforce the restriction. */
return scm_is_pair (x) && GC_is_heap_ptr (SCM2PTR (x));
}
#endif /* BUILDING_LIBGUILE */
SCM_INTERNAL int scm_is_mutable_pair (SCM x);
SCM_API SCM scm_cons2 (SCM w, SCM x, SCM y);
SCM_API SCM scm_pair_p (SCM x);